Alevel Bio question help

Are you doing AQA? As part of my answer will assume you are.

Significant means that any differences between the results/ variables are not likely due to chance (a random event) but more to do with something within the experiment. Not significant means the exact opposite. As an A-level Biology student, you need to be able to determine significance by interpreting a range of data (e.g. standard deviations, P values and outcomes of the three statistical tests you need to be aware of)

Oh right, thank you for clarifying. When there's an overlap between two standard deviations, why is that not significant, because doesn't this then not reduce the chances it being due to chance?